Chaos-Based NOMA for Secure Wireless Communications over Rayleigh Fading Channels

Non-orthogonal multiple access (NOMA) is considered as one of the key technologies to achieve the main targets of fifth generation (5G) wireless networks and beyond such as high user connectivity and ultra-reliability. However, as the number of simultaneously served users increased, the security of users’ data becomes a real concern due to high possibility of unauthorized interception. To mitigate the critical security issue, diverse chaos-based communication systems have been introduced in the literature to provide cost-effective solutions for physical layer security. In this paper, an efficient chaos-based NOMA (CB-NOMA) scheme is proposed for secure wireless transmission. The integrated CB-NOMA design is implemented based on chaotic code-domain with equal power allocation for connected users over Rayleigh fading environment. Different chaotic-code formation scenarios with diverse security levels and implementation complexity are considered for chaos shift keying signalling. Intensive simulation results validate the effectiveness of proposed CB-NOMA compared with the considered reference systems. It shows direct relation between the significant improvement in error performance and utilized lengths of chaotic codes apart from employed code generation source. Besides, beneficial tradeoffs are demonstrated between the achieved error rate, user connectivity, security level, and system complexity.